摘要：The effects of annealing treatments(ATs)on the microstructure of Zr-Sn-Nb alloy strips were *** on the characteristics of strips for nuclear fuel assemblies,punching experiments were carried out and the formability of zirconium alloy strips was quantitatively *** results indicate that the proportions of small-angle grain boundaries of the zirconium alloy under conditions of annealing treatment at 580°C(ATⅠ)and annealing treatment at 620°C(ATⅡ)are 14.3%and 23.2%,respectively,while that of the as-received material is 12.4%.And the forming limit margin fields of the zirconium alloy under ATⅠcan reach 0.43%,while the values of the as-received material and the ATⅡare-0.35%and-2.8%,*** annealing process affects the evolution process of the strip recrystallization texture and the grain ***,the total texture and pole density are closely related to the degree of anisotropy of the ***,the small-angle grain boundary affects the strain path and crack expansion of the necking unit during the strip punching process,while the grain size affects the hardening exponent of the material.

摘要：针对一类非匹配受扰非线性系统在输出受限条件下的跟踪控制问题,本文在预设性能控制过程中引入非递归设计框架,提出了一种降维非递归预设性能控制方案,以缓解常用的递归预设性能控制过程中出现的复杂性爆炸问题,大幅简化了系统的控制器设计过程,便于实际工程应用.本文设计的降维非递归控制策略能够实现控制器设计过程与稳定性分析的分离,并且具有控制器形式简洁、控制参数选取机制简单的优点.最后,选取具有代表性的数值仿真和永磁同步电机位置跟踪控制实验阐释了所提出的控制策略的有效性及简洁性.

摘要：目的探讨中国8个长寿地区≥65岁老年人血尿素氮与肌酐比值和衰弱的关联。方法研究对象来自老年健康生物标志物队列,利用血尿素氮与肌酐的基线信息和随访获得的衰弱事件,将血尿素氮与肌酐比值按五分位数分组,采用Cox比例风险回归模型分析血尿素氮与肌酐比值和衰弱发生风险的关联。结果共纳入1562名研究对象,年龄(81.0±17.0)岁,其中男性814名(52.1%)。(3.73±1.43)年随访期间共发生衰弱事件258名。Cox比例风险回归模型分析结果显示,在调整相关的混杂因素后,与血尿素氮与肌酐比值Q1组相比,Q3、Q4和Q5组的衰弱发生风险分别降低了36%[风险比(HR)=0.64,95%CI:0.43~0.94]、44%(HR=0.56,95%CI:0.38~0.84)和40%(HR=0.60,95%CI:0.41~0.88)。血尿素氮与肌酐比值每增加一个标准差,衰弱发生风险降低20%(HR=0.80,95%CI:0.70~0.91)。血尿素氮与肌酐比值和衰弱发生风险呈近线性剂量-反应关系。结论衰弱发生风险随着血尿素氮与肌酐比值的增加而呈下降趋势,维持较高的血尿素氮与肌酐比值对于预防老年人衰弱具有重要意义。

摘要：针对燃气涡轮二级导向器叶片形状复杂,加工基准多次转换导致加工质量差,生产效率低的现状,提出一种再造加工基准方法:寻找一种低熔点合金配方并设计相应铸型,实现导向器叶片在铸型中的定位,并在其周围浇注形状规则的合金块作为加工基准。该目标合金具有较低的熔点、好的液态流动性、凝固后具有较大的硬度,可保证机加工时装夹稳定、同时具有较高的脆性以保证能够实现机械破碎,脱离导向器叶片;优化后的铸型可保证导向器叶片的定位精度要求以及机加工的精度要求,且避免产生浇注缺陷。

摘要：本文介绍了某县城供暖热源由热电联产集中供热替代原燃煤锅炉热源,有效发挥经超低排放的热电联产集中供热的经济性、环保性、能源可靠性等优势。新建零次侧供热管网自电厂换热首站接至原热源厂内新建隔压泵站,敷设长度约2*10 km,管网管径为DN 800。供热管网敷设途中穿越高速、公路、泾河某支流、排洪沟等特殊地段,根据要求提出了相应的管网敷设解决方案和顶管用保温一体化滑动支架。根据团体标准《长输供热热水管网技术标准》,计算确定了电预热安装设计温度为56℃,供热管网设计和施工整体采用电预热安装无补偿敷设和分布式光纤泄漏监测系统,可以有效保障供热管网长期安全、可靠和经济运行。

摘要：This review mainly summarizes the latest developments in the internal flow field and external characteristics of centrifugal *** particular,the latest findings of centrifugal pumps focused on turbulence and cavitation models,flow visualization methods,and fault detection based on noise and *** external characteristics,cavitation,and vibration of the centrifugal pump were extensively *** addition,advanced multi-objective optimization methods for improving impeller’s efficiency and reducing net positive suction head(NPSH)were *** some progress was made in this field,there remain many unsolved problems,such as monitoring and modeling of cavitation,rotational stall phenomenon,and discrepancies between simulation and *** the future,researchers are encouraged to employ multi-dimensional flow visualization technologies and high-performance computing facilities to advance existing understandings on these issues and create new research directions.

摘要：An ideal current distribution in the air core transformer coils is obtained using variation *** mountain method is utilized for optimizing the dimension and position of the real *** only can the requirement of minimizing the stray field in the plasma region be guaranteed,but also integer turns for the coil can be *** latter brings a significant convenience to engineering.

摘要：为研究大跨度连续梁桥合理的抗震设计方法,以一座(100+160+100)m变截面连续梁桥为背景进行分析。采用动力非线性反应程序SAP2000建立桥梁模型,选取6条实际地震动输入,比较利用桥墩延性进行抗震设计、利用摆式支座进行减隔震设计(分别假设桥墩保持弹性和允许桥墩屈服)时桥梁的地震响应。结果表明:利用桥墩延性抗震设计可能导致固定墩较大的延性需求,从而导致桥墩严重损伤;采用减隔震设计要求桥墩保持弹性,可能导致桥墩较大的地震弯矩和剪力;采用减隔震设计容许桥墩进入延性,可有效减小桥墩的延性需求,从而控制固定墩的损伤。

摘要：研究一种新型汽车扭转阻尼减振器的过流方式(阻尼孔的形状及分布位置和间隙)对减振器性能的影响.提出了2种设计思路综合考虑以阻尼孔为主但含有间隙因素以及不设置阻尼孔只考虑各种间隙因素.分析其阻尼产生原理,基于流体力学有关理论建立了减振器的计算模型,并得到了外特性曲线.两种设计方案有不同的特性,为设计不同结构的扭转减振器提供了依据.

摘要：考虑梗腋在波形钢腹板组合箱梁剪力滞效应的影响,通过剪力流公式定义了考虑梗腋影响的修正系数,运用变分法得到对应的微分方程,然后求出简支波形钢腹板组合箱梁在集中荷载作用下的剪力滞系数计算公式,采用数值模拟进行对比验证。最后通过调整梗腋尺寸参数,研究梗腋形状变化对剪力滞效应的影响。结果表明,考虑梗腋影响后的理论计算结果与有限元结果吻合较好;波形钢腹板组合箱梁的剪力滞效应现象随着梗腋影响系数的增大而减小;考虑梗腋影响的波形钢腹板组合箱梁剪力滞系数较未考虑情况大幅度降低,在集中荷载下剪力滞效应系数减小约10%;当梗腋宽度与上翼板宽度的比值大于0.5时,对剪力滞效应的影响变化较小,梗腋高度为其宽度的0.16~0.19倍时对剪力滞效应影响最大。